The intensive introduction of composites or advanced composite materials in the primary structures of aircraft has become one of the priority objectives in the design and manufacture of a new generation of aircraft, thanks to the possibilities that they provide for their structural optimization.
As is well known, the manufacturing of composite material parts made with polymer resins and fiber reinforcement intended for aeronautic structures involves their curing within a vacuum bag in certain temperature and pressure conditions. It is therefore essential that there be no loss of pressure in the vacuum bag during the curing processes.
Now, since the materials used in the vacuum bags, such as nylon, are materials which are likely to tear, the manufacturing procedures for composite materials have to necessarily include the use of methods for locating pressure losses in the vacuum bags.
The method probably most used in the industry for locating pressure losses in vacuum bags is based upon the use of ultrasound. In fact, the manufacturers of vacuum bags tend to include ultrasound detectors in their catalogs, which convert the ultrasound produced by the pressure losses into audible sounds, which are amplified more the closer the detector is.
There are also other proposals, such as the one described in WO 2008088435, which is based upon incorporating an oxygen sensitive film into the vacuum bag, which changes in appearance when a leak occurs resulting from a loss in pressure, which facilitates its location.
These pressure loss location techniques have significant costs and are not equally adapted to the different sizes of vacuum bags that are used specifically in the aeronautic industry. The ultrasound detectors require a complete inspection of the part, by moving the ultrasound detector close the areas of the part that are likely to have pressure losses. This means significant costs and limits its use to large parts. On the other hand, incorporating a film sensitive to oxygen into the vacuum bag significantly increases its cost.
This invention is directed towards solving those problems.